Annual report pursuant to Section 13 and 15(d)

BENEFIT PLANS (Fair Value of Postretirement Assets) (Details)

v3.6.0.2
BENEFIT PLANS (Fair Value of Postretirement Assets) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Hedge funds, minimum number of days notice prior to redemption 30 days    
Hedge funds, maximum number of days notice prior to redemption 90 days    
Other Benefits      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets $ 16.6 $ 18.9 $ 20.8
Other Benefits | Large-Cap Equity      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [1] 4.5    
Other Benefits | Small- and Mid-Cap Equity      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [1] 1.1    
Other Benefits | International Equity      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [1],[2] 2.0    
Other Benefits | Fixed Income      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets 5.4    
Other Benefits | Private Equity      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [3] 1.2    
Other Benefits | Hedge Funds      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [4] 1.2    
Other Benefits | Real Assets      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets 0.7    
Other Benefits | Cash      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [1] 0.5    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets 6.6    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits | Large-Cap Equity      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [1] 4.5    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits | Small- and Mid-Cap Equity      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [1] 1.1    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits | International Equity      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [1],[2] 0.5    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits | Fixed Income      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits | Private Equity      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [3]    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits | Hedge Funds      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [4]    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits | Real Assets      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits | Cash      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [1] 0.5    
Significant Other Observable Inputs (Level 2) | Other Benefits      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets 6.9    
Significant Other Observable Inputs (Level 2) | Other Benefits | Large-Cap Equity      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [1]    
Significant Other Observable Inputs (Level 2) | Other Benefits | Small- and Mid-Cap Equity      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [1]    
Significant Other Observable Inputs (Level 2) | Other Benefits | International Equity      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [1],[2] 1.5    
Significant Other Observable Inputs (Level 2) | Other Benefits | Fixed Income      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets 5.4    
Significant Other Observable Inputs (Level 2) | Other Benefits | Private Equity      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [3]    
Significant Other Observable Inputs (Level 2) | Other Benefits | Hedge Funds      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [4]    
Significant Other Observable Inputs (Level 2) | Other Benefits | Real Assets      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets    
Significant Other Observable Inputs (Level 2) | Other Benefits | Cash      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [1]    
Significant Unobservable Inputs (Level 3) | Other Benefits      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets 3.1    
Significant Unobservable Inputs (Level 3) | Other Benefits | Large-Cap Equity      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [1]    
Significant Unobservable Inputs (Level 3) | Other Benefits | Small- and Mid-Cap Equity      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [1]    
Significant Unobservable Inputs (Level 3) | Other Benefits | International Equity      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [1],[2]    
Significant Unobservable Inputs (Level 3) | Other Benefits | Fixed Income      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets    
Significant Unobservable Inputs (Level 3) | Other Benefits | Private Equity      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [3] 1.2    
Significant Unobservable Inputs (Level 3) | Other Benefits | Hedge Funds      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [4] 1.2    
Significant Unobservable Inputs (Level 3) | Other Benefits | Real Assets      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets 0.7    
Significant Unobservable Inputs (Level 3) | Other Benefits | Cash      
Weighted-average assumptions used to determine net periodic benefit cost at December 31,      
Fair value of plan assets [1]    
[1] Fair value is based on observable market prices for the assets.
[2] For the portion of this asset class categorized as Level 2, fair value is determined using dealer and broker quotations, certain pricing models, bid prices, quoted prices for similar assets and liabilities in active markets, or other inputs that are observable or can be corroborated by observable market data.
[3] Private equity investments are initially valued at cost. Fund managers periodically review the valuations utilizing subsequent company-specific transactions or deterioration in the company’s financial performance to determine if fair value adjustments are necessary. Private equity investments are typically viewed as long term, less liquid investments with return of capital coming via cash distributions from the sale of underlying fund assets. The Plan intends to hold these investments through each fund’s normal life cycle and wind down period.
[4] Fair value is reported by the fund manager based on observable market prices for actively traded assets within the funds, as well as financial models, comparable financial transactions or other factors relevant to the specific asset for assets with no observable market. These investments are redeemable quarterly with a range of 30 – 90 days notice.